﻿6 BULLETIN 5, U. S. DEPARTMENT OF AGRICULTURE. 



plant 10 inches distant. He also observed that larva? may descend 

 from 8 to 10 inches below the surface of the soil in search of food. 



These observations are substantiated by Mr. George G. Ainslie, who 

 studied the habits of the larva? in the field at Hurricane, Tenn., 

 during May, 1912. In this case, upon digging up the injured corn 

 plants he found that the roots and stem below the ground were 

 grooved, furrowed, and perforated. In many instances there was a 

 distinct perforation into the base of the plant which cut off the 

 crown, thus destroying the central leaves. The larva? were found 

 either in the partly decayed kernel or along the underground stem in 

 the earth. Only occasionally were the larva? found with their heads 

 in these holes in the stem. Mr. Ainslie experienced difficulty in find- 

 ing these larva?, it being necessary to dig over the earth thoroughly 

 for a considerable distance around each plant, some of the larva? 

 being found 4 inches from the injured plant and at a depth of 3 or 4 

 inches. The author also had observed this habit in the young larva? 

 in previous years, and there is always difficulty in reconciling the 

 number of larva? one can obtain in badly infested fields with the 

 damage clearly to be charged to them. In many cases the hole made 

 in the plant is not clean-cut, as shown in figure 1, e, but has some- 

 what the appearance of having been simply bruised. This is prob- 

 ably the work of the young larva?, while the clean-cut hole is the 

 work of those individuals that are larger and more fully developed. 



The larva? of the species under consideration, aside from the work 

 while very young, as described by Mr. Ainslie, eat directly through 

 the outer walls of the base of the plant into the heart of the plant, 

 usually just above the base of the roots, as shown in figure 1, e. The 

 term " rootworm " is somewhat of a misnomer, because these larva? 

 are not usually found in the roots, and as a rule do not feed within 

 them, as is the case with the allied western corn rootworm {Dia- 

 hrotica longicomis) . 



OVIPOSITION. 



The females, which have passed the winter in the adult stage, com- 

 mence egg laying soon after the first warm weather of spring. The 

 statement of Quaintance that the eggs are usually all deposited within 

 the space of two or three days, while perhaps true as a rule, is not 

 entirely borne out by the observations of others. For instance, Mr. 

 R. A. Vickery at Brownsville, Tex., found that one female deposited 

 102 eggs during January 18, 19, and 20; another female deposited 

 22 eggs, 9 on January 19 and 13 on January 28. There does, how- 

 ever, appear to be a tendency on the part of the individual female to 

 complete oviposition within a few days; and this feature in the 

 life history is of considerable economic importance, as it shows that 

 the egg-laying season for the individual in spring is not long drawn 



